When you add a new pricing rule there is an option to choose specific "days of the week."

You can choose only weekends, only weekdays, or choose specific days of the week to apply pricing rules to. This is a great way to increase prices on the weekend. All days are selected by default, and you click on a date to unselect it for that rule. In the screenshot below, there is a pricing rule to increase prices by 20% on Friday and Saturday nights.